Last week, Pfizer announced that the Food and Drug Administration (FDA) has approved its new meningococcal vaccine that covers five serogroups, folding protection against the B group in with coverage against groups A,C, W, and Y.

And yesterday, vaccine advisors to the Centers for Disease Control and Prevention (CDC) recommended that the new vaccine, called Penbraya, can be used when both the four-group (MenACWY) and the monovalent B group (MenB) vaccines are indicated at the same visit for healthy patients ages 16 to 23 and patients ages 10 and older who have certain underlying health conditions.

The approval passed by a 10-to-4 vote. Some members of the Advisory Committee on Immunization Practices (ACIP) were hesitant about the wording of the proposal, due to a desire for a broader recommendation, with some suggesting that the shared decision-making wording isn’t clear.

They also worried about the complexity of managing meningococcal disease vaccination, with doctors juggling another a new type of vaccine alongside two four-group vaccines, which are interchangeable, and two group-B vaccines, which aren’t interchangeable. Other members emphasized that ACIP will continue to look at strategies for boosting uptake of vaccines against the rare but severe disease.

Pfizer in a statement last week said Penbraya, given as two doses 6 months apart, has the potential to protect more adolescents and young adults from a potentially severe disease by providing the broadest coverage with fewer vaccine doses.

The CDC’s director will make a final decision on ACIP’s recommendation.

A multicountry Salmonella enteritidis ST11 outbreak linked to chicken and chicken kebab products since January has sickened at least 335 people from 14 European Union countries, the United Kingdom, and the United States, the European Centre for Disease Prevention and Control (ECDC) announced today.

In early June, Danish officials identified an illness cluster linked to eating chicken, followed by reports of illnesses from other European countries with samples that matched the Danish strain. In late July, Denmark identified a distinct strain, also linked to chicken consumption, followed by reports of a matching strain isolated from several other European countries.

In early August, Austria reported a cluster of related infections involving another distinct strain, including a report of a patient who had consumed a chicken kebab before he or she got sick. In the following weeks, other European countries reported illnesses involving the same strain.

There was only one case from the United States, which was part of the second cluster and involved a patient who had eaten chicken in Spain.

The trace-back investigation suggests that seven producers in Poland and one in Austria may have sourced the products, but microbiologic tests haven’t turned up the outbreak strain at the facilities.

In a rapid risk assessment, the ECDC and the European Food Safety Authority (EFSA) said the cases belong to three distinct microbiologic clusters. Nine people were hospitalized, and one death was reported in Austria. Officials in Austria, Denmark, and Italy tested 10 food products, finding contamination with the outbreak strain in 6, which included contaminated chicken kebabs.

The ECDC said more investigations are needed to identify the source of the infections, and it warned that further cases are likely in the prolonged multicountry outbreak.

A study of three hospitals in Chicago found that increased use of antibiotics at the outset of the COVID-19 pandemic was limited to COVID-19 patients, researchers reported yesterday in Infection Control & Epidemiology.

To determine differences in antibiotic use between COVID-19 and non–COVID-19 patients, a team led by researchers from Rush University Medical Center analyzed electronic health record data from three tertiary acute-care hospitals covering the pre–COVID-19 period (March to December 2019) and the COVID-19 period (March to December 2020). They stratified patients by COVID-19 status, calculated relative percentage differences in antibiotic use in COVID-19 versus non–COVID-19 patients during the two periods, and also compared antibiotic use in non–COVID-19 patients during the two periods.

Facility-wide antibiotic use for all antibiotics was significantly greater in COVID-19 patients compared with non–COVID-19 patients in two of three hospitals during the COVID-19 period, and use of broad-spectrum agents for hospital-onset infections was significantly greater in COVID-19 patients versus non–COVID-19 patients in all three hospitals during both the COVID-19 period (with relative increases of 73%, 66%, and 91% for hospitals A, B, and C, respectively) and the pre–COVID-19 period (with relative increases of 52%, 64%, and 66% for hospitals A, B, and C, respectively).

In contrast, facility-wide antibiotic use for all antibacterial agents was significantly lower in non–COVID-19 patients during the COVID-19 period versus the pre–COVID-19 period (with relative decreases of 8%, 7%, and 8% in hospitals A, B, and C, respectively).

Diagnostic and therapeutic uncertainty

The study authors say the increased use of broad-spectrum antibiotics at the beginning of the pandemic "likely resulted from the diagnostic and therapeutic uncertainty in the context of high mortality rates," while reduced antibiotic use in non–COVID-19 patients during that period could reflect both the durability of antimicrobial stewardship efforts and changes in inpatient populations.

"Elective procedures were deferred, admissions for less critical illnesses were reduced, and the most chronically ill patients who ordinarily would have been admitted for non–COVID-19 indications may instead have been admitted with COVID-19," they wrote.

Bivalent (two-strain) boosters offer some restored protection against critical illness and hospital admission for people who had previously received only two doses of the original mRNA COVID-19 vaccines, according to a study yesterday in The Lancet Respiratory Medicine.

The test-negative case-control study was based on data in the Kaiser Permanente Southern California network. The relative vaccine effectiveness (VE) for people who received a Pfizer-BioNTech bivalent booster was compared to those who received two doses of the original mRNA vaccine. All study participants visited clinics for respiratory infections from August 31, 2022, to April 15, 2023, and were tested for SARS-CoV-2 via polymerase chain reaction tests.

50% VE against critical illness

The study included 24,246 COVID-19 cases and 99,173 test-negative controls. Of the COVID-19 cases, 20,555 infections were caused by Omicron BA.4/5, and 3,691 were related to the XBB strain.

Among those who had received a Pfizer BA.4/5 bivalent booster, relative VE was an additional 50% (95% confidence interval, 23% to 68%) against critical illness, an additional 39% against hospital admission, an additional 35% against emergency department or urgent care visits, and an additional 28% against outpatient encounters.

Though protection against any infection waned from the bivalent booster from 0 to 3 months, then again from 4 to 7 months, the enhanced protection against critical illness, hospital admission, and emergency department or urgent care outcomes remained.

"This important and timely vaccine effectiveness study is a crucial pillar in supporting evidence-based policy making with respect to future vaccination programmes," two Israeli experts wrote in a commentary on the study.